Infant botulism intoxication and autonomic nervous system dysfunction

Abstract

Three infants presenting with severe cases of infantile botulism, occurring at 17, 30, and 180 days of life, respectively, are described in this report. All three infants presented with areflexive flaccid coma or apnoeas requiring prolonged ventilation. In serum, type B botulinum neurotoxin (BoNT/B) was detected in two cases and BoNT/A in the third case, confirming the diagnosis of infantile botulism. Despite constant nursing and monitoring, the recovery of motility was progressive, but finally complete. Dysautonomia, measured by recording heart rate variability (HRV), persisted beyond observable physical recovery. Dysautonomia was assessed using a time-domain analysis of the continuous electrocardiogram response (via non-invasive weekly 24h Holters), which included sympathetic (SDNN) and parasympathetic indices (RMS-SD, pNN50). In all three of our patients, we observed an initial hypotonic period and a major decrease in all HRV indices. Despite observable recovery shortly after extubation, HRV time domain indices remained altered for many weeks. Because of the close monitoring afforded by hospitalization, this change in autonomic function was not accompanied by syncope, complications arising from ventricular arrhythmia, or sudden death. Our observations have important clinical implications since they emphasize the importance of pursuing cardiopulmonary monitoring following apparent functional recovery from the BoNTs.